The present invention relates generally to the use of Ceramic Matrix Composite liners in a gas turbine engine combustor and, in particular, to the mounting of such CMC liners to a support member of the combustor at an aft end so as to accommodate differences in radial and axial growth.
It will be appreciated that the use of non-traditional high temperature materials, such as Ceramic Matrix Composites (CMC), are being studied and utilized as structural components in gas turbine engines. There is particular interest, for example, in making combustor components which are exposed to extreme temperatures from such material in order to improve the operational capability and durability of the engine. As explained in U.S. Pat. No. 6,397,603 to Edmondson et al., substitution of materials having higher temperature capabilities than metals has been difficult in light of the widely disparate coefficients of thermal expansion when different materials are used in adjacent components of the combustor. This can result in a shortening of the life cycle of the components due to thermally induced stresses, particularly when there are rapid temperature fluctuations which can also result in thermal shock.
Accordingly, various schemes have been employed to address problems that are associated with mating parts having differing thermal expansion properties. As seen in U.S. Pat. No. 5,291,732 to Halila, U.S. Pat. No. 5,291,733 to Halila, and U.S. Pat. No. 5,285,632 to Halila, an arrangement is disclosed which permits a metal heat shield to be mounted to a liner made of CMC so that radial expansion therebetween is accommodated. This involves positioning a plurality of circumferentially spaced mount pins through openings in the heat shield and liner so that the liner is able to move relative to the heat shield.
U.S. Pat. No. 6,397,603 to Edmondson et al. also discloses a combustor having a liner made of Ceramic Matrix Composite materials, where the liner is mated with an intermediate liner dome support member in order to accommodate differential thermal expansion without undue stress on the liner. The Edmondson et al. patent further includes the ability to regulate part of the cooling air flow through the interface joint.
Accordingly, it would be desirable for a mounting assembly to be developed for a CMC liner which is able to accommodate differences in axial and radial growth between such liner at an aft end and a support member of the combustor while maintaining the circumferential position of such liner with respect thereto.